Temperature stabilization by inertial feedback control has proven a powerful tool to create the ultrastable environment essential for high resolution calorimetry. A thermally insulated mass, connected to a base through Seebeck effect sensors (thermopiles) is used as a reference to control the base temperature. The thermopile signal is proportional to both the heat capacity of the reference mass and the derivative &THgr;˙ of the base temperature &THgr;. Using vacuum insulation and bismuth telluride thermopiles, we designed and tested temperature derivative sensors (TDSs) with sensitivities up to 3300 V s K−1. Standard industrial controllers with approximately ±1 &mgr;V input noise and stability, permit control of temperature derivatives to ±3×10−10K s−1. Single‐cup thermoelectric calorimeters coupled to the TDS‐controlled base permitted measurement of heat flow from samples in a power range from 3 &mgr;W to 10 W with high accuracy (±100 ppm), resolution (±0.2 &mgr;W), and reproducibility (±1 &mgr;W). The design of two instruments is described in detail. Their performance is demonstrated on a variety of measurements, e.g., the determination of sample heat capacities with temperature ramp rates &THgr;˙=±5×10−6K s−1, the half‐life of a 3 g tritium sample in a uranium getter bed, the decay heat of depleted uranium, and the heat evolution of epoxy resin. ©1996 American Institute of Physics.